1. Field of the Invention
The present invention relates to a system and method for air conditioning by utilizing a phenomenon of evaporation, and more particularly to an air conditioning system and an air conditioning method employing at least two compressors so as to improve the refrigeration efficiency, in which expansion of a refrigerant in an expansion section is controlled according to a used state of the compressors depending on a refrigeration load, so that a general performance of the system can be improved.
2. Description of the Related Art
Main components of an air conditioner are a compressor, an evaporator, an expansion valve and a condenser. Of these main components, the air conditioner has recently shown an increasing tendency to employ a plurality of compressors in order to increase the refrigerating effect. Nowadays, the air conditioner usually employs an air conditioning method utilizing two compressors, since an air conditioner employing more than two compressors has been proved to be disadvantageous in the aspect of the performance ratio to the production ratio.
FIG. 1 is a schematic systematic view of a conventional air conditioning system employing two compressors.
Referring to FIG. 1, the conventional air conditioning system employing two compressors includes a compression section 10 for compressing a gas refrigerant of low temperature and low pressure into a gas refrigerant of high temperature and high pressure by means of two compressors, a condensing section 20 for cooling the gas refrigerant of high temperature and high pressure produced in the compression section 10 into a liquid refrigerant of intermediate temperature and high pressure, an expansion section 30 for depressurizing the liquid refrigerant of intermediate temperature and high pressure produced in the condensing section 20 into a liquid refrigerant of low temperature and low pressure, and an evaporation section 40, in which the liquid refrigerant of low temperature and low pressure produced in the expansion section 30 absorbs heat from its surroundings to be transformed into a gas refrigerant of low temperature and low pressure.
In more detailed description, the compression section 10 is a section, which not only sucks and compresses a gas refrigerant of low temperature and low pressure to make the gas refrigerant transformed into a state, in which it can be liquefied even at a relatively high temperature, but also provides a circulating force for the refrigerant. In this section, it is recently an increasing inclination that two compressors are utilized in order to improve the compression efficiency.
Further, the condensing section 20 is a section, in which the gas refrigerant of high temperature and high pressure produced in the compression section 10 is cooled and liquefied by means of the exterior air applied to the condenser by a fan. In this section, the gas refrigerant of high temperature and high pressure is transformed into the liquid refrigerant of intermediate temperature and high pressure while passing through the condensing section 20.
Moreover, the expansion section 30 is a section, in which the liquid refrigerant of intermediate temperature and high pressure produced in the condensing section 20 is transformed into the liquid refrigerant of low temperature and low pressure mainly by means of the expansion valve.
Further, the evaporation section 40 is a section, in which the liquid refrigerant of low temperature and low pressure produced in the expansion section 30 absorbs heat from its surroundings to be gasified while passing through the evaporator. The surrounding air cooled in this section as described above is sent to an indoor space by a rotation of a fan.
In the air conditioning system utilizing two conventional compressors having the construction as described above, the same expansion section is used as that in the air conditioning system employing one compressor. In this case, this expansion section generally consists of an expansion valve, which is a capillary tube. Consequently, in the air conditioning system employing two compressors, the two compressors may not rapidly cope with the pressure and the flowing quantity of the refrigerant changing according to the operation state of the two compressors, so that the refrigerant can be inversely flown into the compressors again. Further, the temperature of the refrigerant introduced into the compressors through the evaporation section can be increased due to a great change in the flowing quantity of the refrigerant to thereby increase the internal pressure of the compressors, which disturbs a stable operation of the system.
In other words, the conventional expansion valve applies such a large load to the air conditioning system employing two compressors, so as to disturb a smooth operation of the compression section, thereby deteriorating the general function of the system.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and it is an object of the present invention to provide an air conditioning system and an air conditioning method, in which an expansion section can be flexibly operated according to the operation state of at least two compressors, so that the compressors can smoothly operate, to thereby improve the general performance of the system.
In accordance with one aspect, the present invention provides an air conditioning system comprising: a compression section employing at least two compressors, which transform a gas refrigerant of low temperature and low pressure into a gas refrigerant of high temperature and high pressure and enable an operation capacity of the compression section to be changed according to a refrigeration load; a condensing section for transforming the gas refrigerant of high temperature and high pressure, which has been compressed in the compression section, into a liquid refrigerant of intermediate temperature and high pressure; an expansion section employing an electronic expansion valve, which properly expands the liquid refrigerant of intermediate temperature and high pressure, which has been produced in the condensing section, to be transformed into a liquid refrigerant of low temperature and low pressure; an evaporation section for transforming the liquid refrigerant of low temperature and low pressure produced in the expansion section into a gas refrigerant of low temperature and low pressure; temperature sensors respectively disposed at an inlet port of the compression section and an outlet port of the evaporation section to sense temperatures; and a control section for controlling the electronic expansion valve according to a result after dealing with sensed temperatures inputted from the temperature sensors.
In accordance with another aspect, the present invention provides an air conditioning method by an air conditioning system including a compression section and an evaporation section, the method comprising: a temperature difference measuring step, in which temperatures are measured by temperature sensors respectively disposed at an inlet port of IC the compression section and at an outlet port of the evaporation section, so as to estimate a degree of superheat, which is a value obtained by subtracting a first temperature at the outlet port of the evaporation section from a second temperature at the inlet port of the compression section; a superheated degree comparison step, in which an estimated degree of superheat estimated in the temperature difference measuring step is compared with a target degree of superheat; and a superheated degree compensation step, in which a difference of superheated degrees is compensated when the estimated degree of superheat is different from the target degree of superheat as a result of a comparison in the superheated degree comparison step.
In the air conditioning system and method according to the present invention, at least two compressors are employed so as to improve the refrigeration efficiency, and an opening state of an expansion section is controlled correspondingly to an operated state of the compressors, so as to reduce the negative load applied to the compressors due to the changes in the flowing quantity and the pressure of the refrigerant according to the state of the operated compressor, so that a general performance of the system can be improved.
In this case, measurement of the changes in the flowing quantity and the pressure of the refrigerant, which is necessary in order to control the opening state of the expansion section, can be executed by sensing and comparing the temperatures at the outlet port of the evaporation section and at the inlet port of the compression section, which show a temperature difference according to the flowing quantity and the pressure of the refrigerant. Therefore, the air conditioning system and method of the present invention achieves a simple construction, which can be easily assembled and enables the manufacturing cost to be reduced.